On July 24, 2015 (June 9, 2015 in the lunar calendar), NASA announced the discovery of the "Other Earth" similarity index of 0.98. At 0:00 a.m. Beijing time on July 24, 2015, NASA held a media conference call to announce the latest discovery of the Kepler Space Telescope: Astronomers said that the exoplanet closest to "another Earth" has been discovered so far. The planet's name is Kepler 452b, which has a similarity index of 0.98 to Earth. The picture shows an artistic imagination of a newly discovered planet, called kepler-452b, with a diameter 60% larger than Earth. Astronomers say this is the closest "twin planet" to Earth discovered so far and may have an atmosphere and flowing water. Scientists speculate that Kepler 452b is an earth-like planet because the star it orbits is larger than the sun and is similar to the distance from the star to the Earth. The planet may have begun to enter a runaway greenhouse effect stage. It is likely to become a "super gold star" in the future. The picture shows a comparison of the size of Earth and kepler-452b. The planet is 1400 light-years away from Earth and orbits a star very similar to the Sun. That star has 4% more mass than the sun and 10% more brightness. Kepler-452b is the same distance from that star as the earth is from the sun. The picture shows a comparison between the Kepler telescope's previously discovered galaxy kepler-186 and the galaxy where kepler-452b is located, our solar system. Because the stars of the Kepler-186 system are much smaller than the Sun, almost all of its major planets are very close to the stars, about the same orbit as Mercury in our solar system. Kepler's next mission will officially kick off in 2017: finding habitable planets around nearby stars. NASA said Kepler 452b is known as Earth 2.0. The picture shows a comparison of Kepler-452b planet and the Earth released by NASA. Kepler Telescope How to Find Kepler According to a professor at the Department of Astronomy at the School of Physics at Peking University, the Kepler Telescope's method of finding extrasolar planets is mainly achieved by observing the brightness of stars, which is equivalent to waiting for them, guarding hundreds of stars, stare. When the planet rotates around the star and blocks the star, the brightness of the star seen by the Kepler telescope will change, and the brightness of the star will become dimmer. If the planet is large, the brightness of the star will be greater because the blocking area is a little more. On the contrary, if the planet is small, the brightness change will not be so large, so it is not easy to observe. In addition to the small changes in brightness that are difficult to measure, finding exoplanets similar to the size of the Earth also places high requirements on telescope measurement accuracy. Even if it is found, more telescope observations will be needed to confirm it. Is there life on the "other earth"? The authors of the proposal measured the diameter of Kepler 452b based on observation data. Based on the measurement data, they determined that the planet may have an atmosphere and a large amount of water. This is not enough to determine whether life really exists on the planet. Wu Xuebing introduced that in addition to size, concepts similar to the Earth include whether it is suitable for the existence of life like the Earth. The Kepler telescope cannot analyze the composition of distant planets, so it can only judge whether there is water and suitable for the existence of life based on the distance of the planet from the star. If it is too close, the temperature will be higher. If it is too far, the temperature will be lower. Only a distance like the earth and the sun can be suitable for the existence of life. This is called the habitable zone. If it is in the habitable zone, it will be more similar to the earth's ecological environment. The Kepler telescope, launched in 2009, has so far confirmed more than 1000 extrasolar planets and more than 3000 planet candidates, of varying sizes and orbits, some in the habitable zone. Immigrant "close relatives of earth"? Even if the discovery of "another earth" is too far away, does it mean that it can move from the science fiction world to the real world? Can humans visit it? In fact, the nearest earth-like planets are all light-years away from Earth. Wu Xuebing said that stars outside the solar system are too far away for humans, and light takes many years to travel and is impossible to reach them. So from a practical perspective, it is impossible to immigrate to the past. But for astronomy, if humans really discover that there are Earth-like systems in the universe, this will be very meaningful. It will be very helpful for humans to understand the universe and other star systems. The Kepler mission was launched on March 7, 2009. During 2329 days in space, 306604 stars were observed. More than 4660 candidate exoplanets were discovered. More than 1024 confirmed exoplanets. 9 confirmed livable planets.